The present invention relates to seat backrests with layered structures and has been developed specifically for the production of backrests for front or rear seats for motor vehicles.
The main function of the backrest of a seat is to provide support for the vertebral column of the occupant so as to offer the required comfort: in other words, the backrest of a seat provides differentiated support for the vertebral column of the occupant so as to satisfy his anatomical and functional requirements.
The production of seat backrests of this type, particularly for automotive use, leads to a search for the best compromise between the need to provide the best driving and travelling comfort and at the same time to reduce the complexity and hence the cost of the backrest structure, as well as the transverse size (thickness) of the backrest in order to make more useful space available within the passenger compartment of the motor vehicle.
A motor vehicle seat comprising a squab and a backrest having padding with a layered structure has already been proposed by the Applicant (Italian patent application No. IT-A-67887/88).
For cars of a certain class, it has already been proposed to provide car seats with backrests including mechanisms by means of which the profile of the backrest in the vertical direction can be modified in order to enable the backrest to be adapted to the typical shape of any occupant's vertebral column. However, these systems are complicated and expensive, and also require space within the backrest such that the backrest has to be very thick in order to retain sufficient padding and hence travelling comfort, or the padding has to be thinner in order to keep the overall thickness of the backrest the same as that of a backrest without a mechanism for adapting its shape, with the result that the backrest is less comfortable.